Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

RE: OCBF Requirements

[Subject Prev][Subject Next][Thread Prev][Thread Next]
The metal building people got nailed on that one for no good reason.  They had to put in the exception to allow tension only to keep all of the thousands of metal buildings standing.  It was one of those code developer oops moments. 

Regards, Harold Sprague

Date: Thu, 20 Nov 2008 20:36:29 -0500
From: gtg740p(--nospam--at)
To: seaint(--nospam--at)
Subject: Re: OCBF Requirements

I remember reading you can use tension only now but I am not sure about a line of resistance that has a compression only diagonal. I am not sure I would want to do that anyway. But it may still be allowed by AISC, I am not sure.
Will H

On Thu, Nov 20, 2008 at 8:20 PM, Yousefi, Ben <Ben.Yousefi(--nospam--at)> wrote:
That is only a requirement for SCBF's (see section 13.2c of AISC 341). For OCBF's it is not an issue.

Ben Yousefi, SE, CBO
Chief Building Official
City of Mountain View, CA
(650) 526-7007

From: Larry Hauer [mailto:lhauer(--nospam--at)]
Sent: Thursday, November 20, 2008 5:10 PM
To: Struct. Eng. Assoc.
Subject: OCBF Requirements


I am designing a small one story steel framed processing facility using an R=3.25 for OCBF's and a Seismic Design Catagory E due to the S sub1 being high. The IBC/CBC references the AISC 341 for designing OCBF's which gives requirements for "V" and inverted "V" type bracing, but doesn't mention single bracing. The design example in the AISC Seismic Design manual for OCBF's is a single diagonal brace between 2 columns.
My question is: Is it permissible to use a single diagonal brace for a line of resistance, which would act either in tensiion or compression to resist seismic forces? I remember something in the '97 UBC about you couldn't use "tension only" bracing, (with some exceptions), but can't find any restrictions in the CBC/IBC, AISC, ASCE, etc., other than the fact that the referenced AISC 341 doesn't mention them.
Thanks in advance,
Larry Hauer, S.E.

Proud to be a PC? Show the world. Download the "I'm a PC" Messenger themepack now. Download now.

Proud to be a PC? Show the world. Download the “I’m a PC” Messenger themepack now. Download now.